Interferons (IFNs) are a group of proteins, some of which are glycosylated, that elicit a variety of cellular responses. These effects include the induction of an antiviral state, inhibition of cell proliferation and modulation of immune responses. The antiviral activity, and possibly the other biological effects of IFN, involve the cellular activation of specific gene products. Friedman, et al., Cell, 38: 745 (1984). The initial step required for the induction of these events within the cells appears to be the binding of IFN to its specific cell surface receptors. This may be followed by the internalization of the IFN-receptor complex and the degradation of the IFN molecules in the lysosome. Branca, et al., J. Biol. Chem. 257: 13291 (1982); Feinstein, et al., J. Interf. Res., 5:65 (1985); Yonehara, et al., J. Gen. Virol., 64: 2409 (1983); Sarkar and Gupta, Eur. J. Biochem., 461 (1984). Alternatively, the interaction of IFN with its specific binding site may stimulate a transmembrane signal which triggers IFN-induced cellular responses.
The ability of interferon to induce antiviral activity has been shown to depend on initial binding of interferon to a specific cell surface receptor. Zoon, Pharmac. Ther., 24: 259-78 (1984); Friedman, Science, 156: 1760-61 (1967); Stewart II, et al., J. Virol., 10:707-712 (1072); Berman and Vilcek, Virology, 57: 378-86 (1974); Branca, et al., J. Biol. Chem., 257:13291-96 (1982); Zoon, et al., Virology, 130:195-203 (1983).
Joshi et al., (1982) covalently bound radiolabeled IFN-alpha-2 to its receptor on Daudi cells, a human lymphoblastoid cell line. They identified, by polyacrylamide gel electrophoresis, a discrete IFN-receptor complex with an apparent molecular weight (mr) of 150,000 daltons.
Faltynek, et al., PNAS, 80: 3269-73 (1983) solubilized the interferon receptor of lymphoblastoid Daudi cells and reported on its binding properties and physical characteristics.
Eid and Mogensen, FEBS Lett., 156:157-160 (1983) extracted and stabilized an allegedly homogeneous, 230,000 dalton complex of interferon bound to interferon receptor. They also detected a second interferon complex, active at 37.degree. C. See also Mogensen, et al. Am. J. Cancer, 28: 575-82 (1981); Mogensen and Bandu, Eur. J. Biochem. 134: 355 (1983). The second complex was believed to represent a transfer of interferon to an activation complex on the cell membrane.
Branca and Baglioni, Nature, 294:768-770 (1981) reported that Daudi cells express a homogeneous population of receptors for IFN alpha-A, but this finding was challenged by Hannigan, et al., J. Biol. Chem., 259, 9456-60 (1984).
Traub, et al., J. Biol. Chem. 258: 13872-77 (Nov. 25, 1984) described the partial purification of alpha interferon receptor activity from human lymphoblastoid cells. The "receptor" was characterized only by stokes radius (74 angstroms) and sedimentation coefficient (13.6S). The stokes radius was between that of thyroglobulin (660,000D) and apoferritin (460,000D). The sedimentation coefficient was between that of galactosidase and catalase. These figures may reflect the formation of micelles of the receptor protein with the Triton detergent employed. There is no suggestion in this paper that there might be more than one receptor present.
The following articles relate to the isolation, purification, and use of other receptor proteins: Hack, et al., Nature, 277:403 (1979) (EGF); Cohen, et al., J. Biol. Chem, 255:4834 (1980) (EGF); Siegel, et al., J. Biol. Chem., 256:9266 (1981) (insulin); Jacobs, et al., 80:1228 (1983) (insulin); Jacobs, et al., Biochem. & Biophys. Res Commun., 77:981 (1977) (insulin); Petruzzelli, et al., DNAS, 81:3327 (1984) (insulin); Greene, et al., PNAS, 77:5115 (1980) (estrogen); Oppenheimer and Czech, J. Biol. Chem., 258:8539 (1983) (rat) IGF II); Cuatrecasas, PNAS, 69:1277 (1972) (insulin).
It has recently been reported that an anti-idiotypic monoclonal antibody was made using rabbit anti-IFN-alpha as the antigen. Osheroff, J. Immunol., 135:306 (1985). This monoclonal antibody (McAb) can recognize human IFN-alpha receptors. Our approach to produce anti-IFN-receptor antibodies employed a different antigen, i.e. the human Type I (alpha and beta) IFN receptor itself.
Our own work was first described by us at the 17th Miami Winter Symposium, Advances in Gene Technology: Molecular Biology of the Immune System, in an Abstract by L. A. Cook, M. J. Liao, S. Scott, and D. Testa, entitled, "Characterization and Affinity Purification of Alpha Interferon Receptor," presented no earlier than Feb. 11, 1985. It was subsequently presented at the TNO-ISIR Meeting on the Interferon System, Oct. 13-18, 1985; and at the 14th Annual Meeting of the ISEM, in Israel. These abstracts relate to prior work which does not qualify as prior art.
At the October, 1985 meeting, French researchers Eid and Mogenson reported the separation of IFN-receptor complexes of 650 and 175 kD, and speculated as to the existence of a 100 kD IFN binding protein. This was subsequent to our work and outside the scope of prior art. Moreover, they did not suggest the existence of the lower molecular weight IFN binding protein which we discovered.